U.S. patent application number 10/551192 was filed with the patent office on 2006-09-28 for composite of support matrix and collagen, and process for producing support substrate and composite.
Invention is credited to Yukako Fukuhira, Hiroaki Kaneko, Eiichi Kitazono, Takanori Miyoshi, Yoshihiko Sumi.
Application Number | 20060216320 10/551192 |
Document ID | / |
Family ID | 33134315 |
Filed Date | 2006-09-28 |
United States Patent
Application |
20060216320 |
Kind Code |
A1 |
Kitazono; Eiichi ; et
al. |
September 28, 2006 |
Composite of support matrix and collagen, and process for producing
support substrate and composite
Abstract
A cylindrical body is produced which is composed of a fiber
structure with a basis weight of 1-50 g/m.sup.2 and having a
diameter of 0.5-50 mm and a bellows-shaped section, wherein the
crest-to-crest spacing of the bellows-shaped section is no greater
than 2 mm and the crest-to-valley depth of the bellows-shaped
section is 0.01-1 mm; collagen is added to the cylindrical body to
produce a composite comprising the cylindrical body and
collagen.
Inventors: |
Kitazono; Eiichi; (Tokyo,
JP) ; Miyoshi; Takanori; (Tokyo, JP) ; Kaneko;
Hiroaki; (Tokyo, JP) ; Sumi; Yoshihiko;
(Tokyo, JP) ; Fukuhira; Yukako; (Tokyo,
JP) |
Correspondence
Address: |
SUGHRUE MION, PLLC
2100 PENNSYLVANIA AVENUE, N.W.
SUITE 800
WASHINGTON
DC
20037
US
|
Family ID: |
33134315 |
Appl. No.: |
10/551192 |
Filed: |
March 31, 2004 |
PCT Filed: |
March 31, 2004 |
PCT NO: |
PCT/JP04/04620 |
371 Date: |
September 29, 2005 |
Current U.S.
Class: |
424/422 ;
623/1.11 |
Current CPC
Class: |
A61F 2/06 20130101; A61F
2210/0004 20130101; A61L 27/34 20130101; A61L 27/34 20130101; C08L
89/06 20130101 |
Class at
Publication: |
424/422 ;
623/001.11 |
International
Class: |
A61F 2/06 20060101
A61F002/06 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 31, 2003 |
JP |
2003-094399 |
Nov 13, 2003 |
JP |
2003-383432 |
Claims
1. A composite comprising collagen and a support matrix made of a
fiber structure composed of aliphatic polyester fibers with a mean
fiber size of 0.05-50 .mu.m.
2. A composite according to claim 1, wherein said fiber structure
is a biodegradable polymer.
3. A composite according to claim 2, wherein said fiber structure
is an aliphatic polyester.
4. A composite according to claim 3, wherein said aliphatic
polyester is polylactic acid, polyglycolic acid, polycaprolactone
or a copolymer thereof.
5. A composite according to claim 1, wherein said support matrix is
a cylindrical body with a bellows-shaped section.
6. A composite according to claim 5, wherein said cylindrical body
is a cylindrical body which is composed of a fiber structure with a
basis weight of 1-50 g/m.sup.2 and has a membrane thickness of
0.05-0.2 mm and a diameter of 0.5-50 mm, wherein the spacing of the
bellows-shaped section is no greater than 2 mm and the depth of the
bellows-shaped section is 0.1-10 mm.
7. A cylindrical body characterized by being composed of a fiber
structure with a basis weight of 1-50 g/m.sup.2 and having a
membrane thickness of 0.05-0.2 mm and a diameter of 0.5-50 mm,
wherein the spacing of the bellows-shaped section is no greater
than 2 mm and the depth of the bellows-shaped section is 0.1-10
mm.
8. A cylindrical body according to claim 7, wherein said
cylindrical body is a biodegradable polymer.
9. A composite according to claim 8, wherein said fiber structure
is an aliphatic polyester.
10. A cylindrical body according to claim 9, wherein said aliphatic
polyester is polylactic acid, polyglycolic acid, polycaprolactone
or a copolymer thereof.
11. A cylindrical body according to claim 7, wherein the mean fiber
size of said cylindrical body is 0.05-50 .mu.m.
12. A method for production of a cylindrical body composed of a
fiber structure with a basis weight of 1-50 g/m.sup.2, wherein the
spacing of the bellows-shaped section is no greater than 2 mm and
the depth of the bellows-shaped section is 0.01-0.1 mm, which
method comprises a stage of producing a solution of an aliphatic
polyester in a volatile solvent, a stage of spinning said solution
by an electrostatic spinning method, a stage of obtaining a fiber
structure accumulated on a collector, and a stage of molding said
fiber structure into a cylindrical body having a bellows-shaped
section with a spacing of no greater than 2 mm.
13. A method for production of a composite composed of a
cylindrical body and collagen, wherein a composite is formed of a
cylindrical body produced by a method according to claim 12, and
collagen.
14. A method for production of a composite composed of a
cylindrical body and collagen, wherein a cylindrical body produced
by a method according to claim 12 is impregnated with a solution
comprising collagen dissolved and/or dispersed in a solvent, and
then at least one method is employed to fix the collagen by
gelling, crosslinking or drying.
Description
TECHNICAL FIELD
[0001] The present invention relates to a composite composed of
collagen and a support matrix made of a fiber structure composed of
aliphatic polyester fibers with a mean fiber size of 0.05-50 .mu.m,
to a cylindrical support matrix having a bellows-shaped section,
and to a method for production of the support matrix and a method
for production of the composite.
BACKGROUND ART
[0002] Recent years have seen an increase in active research in
regenerative medicine, a technical field which takes advantage of
the ability of cells to differentiate and proliferate to achieve
reconstruction of original biological tissues and organs, as a
method for treating major injury to or loss of biological tissue
and organs. Neural regeneration is a branch of this field, and
research is underway toward using tubes composed of artificial
materials for crosslinking between stumps in the neuron-deficient
sites of patients with ablated neural tissue, to induce
regeneration of the neural tissue. Such tubes are made of silicon,
polyurethane, polylactic acid, polyglycolic acid, polycaprolactone
or their copolymers or composites, and they are often internally
coated with collagen or laminin.
[0003] For vascular regeneration there are used artificial material
tubes made of polytetrafluoroethylene, polyester, polylactic acid,
polyglycolic acid, polycaprolactone or their copolymers or
composites, and these are also often internally coated with
gelatin, albumin, collagen or laminin.
[0004] For example, Japanese Unexamined Patent Publication HEI No.
6-285150 describes artificial vessels obtained by injecting
insoluble collagen into the walls of cylindrical tubes made of a
fibrous substance, and then subjecting them to chemical treatment
before drying.
[0005] Also, Japanese Unexamined Patent Publication HEI No.
7-148243 discloses an implant material whose matrix is a
biocompatible bulky structure comprising organic fibers in a
three-dimensional woven texture or knitted texture, or a composite
texture obtained as a combination thereof, wherein the void
fraction of the texture is preferably 20-90 vol %.
[0006] Japanese Unexamined Patent Publication HEI No. 8-294530
describes a cardiovascular restorative material characterized by
insolubilizing a bioabsorbable substance attached to a porous
matrix by at least one means having a physical effect of wet
swelling by entanglement, heat treatment and charging.
[0007] Japanese Unexamined Patent Publication HEI No. 8-33661
describes an artificial vessel obtained by coacervation of
water-soluble elastin and fixing with a crosslinking agent, either
directly or after coating of gelatin or collagen and fixing with a
crosslinking agent, onto the lumen surface of an artificial vessel
matrix made of a synthetic resin.
[0008] Also, Japanese Unexamined Patent Publication HEI No.
9-173361 describes an artificial vessel obtained by coating of
albumin onto the lumen surface of an artificial vessel matrix made
of a synthetic resin, and heating thereof or further crosslinking
thereof with a crosslinking agent after the heating to construct an
albumin layer, followed by coacervation of water-soluble elastin
thereover and fixing with a crosslinking agent.
[0009] Japanese Unexamined Patent Publication No. 2003-126125
describes an artificial vessel having a cylindrical porous
artificial vessel matrix, wherein the pores of the porous
artificial vessel matrix are impregnated with a gel solution
containing a biofunctional substance.
[0010] These publications describe tubes having synthetic resins
woven into a plain weave or knit as the matrix for an artificial
vessel, nonwoven fabric tubes formed from a synthetic resin shaped
into a filament and roll laminated on a mandrel, or tubes obtained
by extrusion molding of a mixture of a synthetic resin and a
particulate aqueous solution of sodium chloride, but all of these
methods yield artificial vessel matrix tubes which lack
stretchability and have unsatisfactory Young's moduli.
[0011] A modification for improving stretchability by means of a
special shape is described in Japanese Unexamined Patent
Publication HEI No. 5-23362, which discloses an artificial tube
obtained by using multifilament yarn composed of polyester
ultrafine filaments as the warp and weft yarns, and hollow weaving
to yield a seamless tube which is then worked to form a
bellows-shaped section.
[0012] Also, Japanese Unexamined Patent Publication HEI No. 8-71093
discloses a modification whereby pleats are added to a conical
fabric prosthetic vessel whose starting material is a fiber
material.
[0013] Since the aforementioned silicon, polyurethane,
polytetrafluoroethylene and polyester materials lack bioabsorption
properties, they are associated with problems from the standpoint
of long-term safety, while compression and damage to regenerated
nerves and vessels is also a concern. Also, polylactic acid,
polyglycolic acid, polycaprolactone and their copolymers, while
having bioabsorption properties, are problematic in terms of
Young's modulus and stretchability, and can likewise lead to
compression and damage to regenerated nerves and vessels. In other
words, no tubes are known at the current time which exhibit
superior performance from the standpoint of bioabsorption, Young's
modulus and stretchability.
[0014] These problems can potentially be overcome by using
composites of elastic materials such as collagen with support
matrices made of polylactic acid, polyglycolic acid,
polycaprolactone and their copolymers, but since conventionally
known support matrices made of polylactic acid, polyglycolic acid,
polycaprolactone and their copolymers lack stretchability, they
counter the elastic property of the collagen and thus limit the use
of such materials in the body. In other words, the currently known
support matrices made of polylactic acid, polyglycolic acid,
polycaprolactone and their copolymers, and composites of such
support matrices with collagen, do not exhibit excellent
stretchability.
DISCLOSURE OF THE INVENTION
[0015] It is an object of the present invention to provide a matrix
having high stretchability and an adequate Young's modulus (elastic
modulus), as a tube which can serve as the matrix for an artificial
vessel or for neural regeneration.
[0016] More specifically, the object is to provide such a matrix
wherein the tube is a polymer compound having a bioabsorption
property.
[0017] The aspects of the present invention are as follows.
[0018] 1. A composite comprising collagen and a support matrix made
of a fiber structure composed of aliphatic polyester fibers with a
mean fiber size of 0.05-50 .mu.m.
[0019] 2. A composite according to aspect 1 of the invention,
wherein the fiber structure is a biodegradable polymer.
[0020] 3. A composite according to aspect 2 of the invention,
wherein the fiber structure is an aliphatic polyester.
[0021] 4. A composite according to aspect 3 of the invention,
wherein the aliphatic polyester is polylactic acid, polyglycolic
acid, polycaprolactone or a copolymer thereof.
[0022] 5. A composite according to aspect 1 of the invention,
wherein the support matrix is a cylindrical body with a
bellows-shaped section.
[0023] 6. A composite according to aspect 5 of the invention,
wherein the cylindrical body is a cylindrical body which is
composed of a fiber structure with a basis weight of 1-50 g/m.sup.2
and has a membrane thickness of 0.05-0.2 mm and a diameter of
0.5-50 mm, wherein the spacing of the bellows-shaped section is no
greater than 2 mm and the depth of the bellows-shaped section is
0.1-10 mm.
[0024] 7. A cylindrical body characterized by being composed of a
fiber structure with a basis weight of 1-50 g/m.sup.2 and having a
membrane thickness of 0.05-0.2 mm and a diameter of 0.5-50 mm,
wherein the spacing of the bellows-shaped section is no greater
than 2 mm and the depth of the bellows-shaped section is 0.1-10
mm.
[0025] 8. A cylindrical body according to aspect 7 of the
invention, wherein the cylindrical body is a biodegradable
polymer.
[0026] 9. A composite according to aspect 8 of the invention,
wherein the fiber structure is an aliphatic polyester.
[0027] 10. A cylindrical body according to aspect 9 of the
invention, wherein the aliphatic polyester is polylactic acid,
polyglycolic acid, polycaprolactone or a copolymer thereof.
[0028] 11. A cylindrical body according to aspect 7 of the
invention, wherein the mean fiber size of the cylindrical body is
0.05-50 .mu.m.
[0029] 12. A method for production of a cylindrical body composed
of a fiber structure with a basis weight of 1-50 g/m.sup.2, wherein
the spacing of the bellows-shaped section is no greater than 2 mm
and the depth of the bellows-shaped section is 0.01-0.1 mm, which
method comprises a stage of producing a solution of an aliphatic
polyester in a volatile solvent, a stage of spinning the solution
by an electrostatic spinning method, a stage of obtaining a fiber
structure accumulated on a collector, and a stage of molding the
fiber structure into a cylindrical body having a bellows-shaped
section with a spacing of no greater than 2 mm.
[0030] 13. A method for production of a composite composed of a
cylindrical body and collagen, wherein a composite is formed of a
cylindrical body produced by a method according to aspect 12 of the
invention, and collagen.
[0031] 14. A method for production of a composite composed of a
cylindrical body and collagen, wherein a cylindrical body produced
by a method according to aspect 12 of the invention is impregnated
with a solution comprising collagen dissolved and/or dispersed in a
solvent, and then at least one method is employed to fix the
collagen by gelling, crosslinking or drying.
BRIEF EXPLANATION OF THE DRAWINGS
[0032] FIG. 1 is an example of an apparatus used in an
electrostatic spinning method wherein the spinning solution is
discharged into an electrostatic field, as a production method of
the invention.
[0033] FIG. 2 is an example of an apparatus used in an
electrostatic spinning method wherein fine droplets of the spinning
solution are introduced into an electrostatic field, as a
production method of the invention.
[0034] FIG. 3 is a cross-sectional view of a cylindrical body
according to the invention.
BEST MODE FOR CARRYING OUT THE INVENTION
[0035] The present invention will now be explained in greater
detail. The examples and explanation which follows are only
illustrative of the invention and, needless to mention,
modifications may be implemented which are within the scope of the
invention.
[0036] The fiber structure used for the invention may be a
three-dimensional structure formed by laminating and accumulating
single or multiple filaments. The form of the structure may be, for
example, a nonwoven fabric, woven fabric, knitted fabric, mesh,
yarn or the like.
[0037] The composite used for the invention is a composite composed
of the aforementioned fiber structure and collagen.
[0038] The fiber structure used for the invention is made of an
aliphatic polyester.
[0039] As aliphatic polyesters there may be mentioned polylactic
acid, polyglycolic acid, lactic acid-glycolic acid copolymer,
polycaprolactone, polybutylene succinate, polyethylene succinate
and their copolymers. Preferred aliphatic polyesters among these
are polylactic acid, polyglycolic acid, lactic acid-glycolic acid
copolymer and polycaprolactone, with polylactic acid and
polycaprolactone being particularly preferred.
[0040] The fiber structure used for the invention is preferably a
cylindrical body with a bellows-shaped section.
[0041] The fiber structure of the invention has a basis weight of
1-50 g/m.sup.2, and is preferably not less than 1 g/m.sup.2 because
a structure will not be satisfactorily formed. It is also
preferably not greater than 50 g/m.sup.2 because the stretchability
will be impaired when it is molded into a tube. A more preferred
basis weight range is 5-30 g/m.sup.2, and a particularly preferred
basis weight range is 5-20 g/m.sup.2.
[0042] The membrane thickness of the fiber structure is preferably
0.05-0.2 mm, and more preferably 0.1-0.18 mm.
[0043] The fiber structure of the invention is a cylindrical body
with a diameter of 0.5-50 mm, wherein the spacing of the
bellows-shaped section is no greater than 2 mm and the depth of the
bellows-shaped section is 0.1-10 mm, because if the spacing is
greater than 2 mm, the stretchability will be impaired when it is
molded into a tube. The spacing of the bellows-shaped section is
more preferably no greater than 1 mm.
[0044] The fiber structure of the invention is formed from fibers
with a mean fiber size of 0.05-50 .mu.m. The mean fiber size is
preferably not less than 0.05 .mu.m because the strength of the
fiber structure will not be maintained. The mean fiber size is also
preferably not greater than 50 .mu.m because the stretchability may
be reduced during molding into a tube, thus impairing the elastic
modulus. A more preferred range for the mean fiber size is 0.2-25
.mu.m, and a particularly preferred range for the mean fiber size
is 0.2-20 .mu.m. The range is most preferably 0.3-10 .mu.m. The
fiber size is the diameter of a fiber cross-section.
[0045] The mechanical properties of the fiber structure of the
invention are preferably such that the Young's modulus is
1.times.10.sup.2-1.times.10.sup.7 Pa and the yield elongation is
20% or greater. A Young's modulus of less than 1.times.10.sup.2 or
greater than 2.times.10.sup.7, or a yield elongation of less than
20%, can lead to problems in terms of elasticity and
stretchability, as well as compression and damage to regenerated
neurons or vessels.
[0046] The method of producing the fiber structure of the invention
may be an electrostatic spinning method, a spun bond method, a melt
blow method, a flash spinning method or the like. Electrostatic
spinning is preferred among these methods. In an electrostatic
spinning method, a solution of the aliphatic polyester in a
volatile solvent is discharged into an electrostatic field formed
between electrodes, and the solution is drawn toward the electrodes
and the formed fiber substance is collected. "Fibrous substance"
includes not only one having the solvent of the solution already
distilled off to form a fiber structure state, but also a substance
still containing the solution solvent. The electrodes used for the
invention may be composed of any type of substance which exhibits
conductivity, such as metal or an inorganic or organic substance.
They may also each consist of an insulator coated with a thin film
of a conductive metal, inorganic or organic substance. The
electrostatic field of the invention is formed between a pair of or
more electrodes, and a high voltage may be applied to any of the
electrodes. This includes, for example, cases using a total of
three electrodes, i.e. two high-voltage electrodes with different
voltage levels (for example, 15 kV and 10 kV) and an electrode
which is grounded, as well as cases using more than three
electrodes.
[0047] The concentration of the aliphatic polyester in the
aliphatic polyester solution according to the invention is
preferably 1-30 wt %. The concentration of the aliphatic polyester
is preferably not less than 1 wt % because such a low concentration
will make it difficult to form a fiber structure. It is also
preferably not greater than 30 wt % because the fiber size of the
resulting fiber structure will be too large. The concentration of
the aliphatic polyester is more preferably 2-20 wt %.
[0048] The volatile solvent used to form the solution of the
invention is a substance which dissolves the aliphatic polyester,
has a boiling point of no greater than 200.degree. C. at ordinary
pressure, and is liquid at 27.degree. C.
[0049] As examples of specific volatile solvents there may be
mentioned methylene chloride, chloroform, acetone, methanol,
ethanol, propanol, isopropanol, toluene, tetrahydrofuran,
1,1,1,3,3,3-hexafluoroisopropanol, water, 1,4-dioxane, carbon
tetrachloride, cyclohexane, cyclohexanone, N,N-dimethylformamide
and acetonitrile. Particularly preferred among these are methylene
chloride, chloroform and acetone, from the standpoint of solubility
of the aliphatic polyester.
[0050] These solvents may be used alone or in combinations of two
or more. According to the invention, other solvents may also be
used therewith so long as the object of the invention is not
prevented.
[0051] The following is a brief description of the reference
numerals used in FIGS. 1 to 3. [0052] 1 Solution ejection nozzle
[0053] 2 Solution [0054] 3 Solution holding tank [0055] 4 Electrode
[0056] 5 Fiber substance collecting electrode [0057] 6 High-voltage
generator [0058] 7 Solution ejection nozzle [0059] 8 Solution
[0060] 9 Solution holding tank [0061] 10 Electrode [0062] 11 Fiber
substance collecting electrode [0063] 12 High-voltage generator
[0064] 13 Thickness [0065] 14 Bellows-shaped section spacing [0066]
15 Depth [0067] 16 Diameter
[0068] Any desired method may be used for discharge of the solution
into the electrostatic field. An example will now be explained with
reference to FIG. 1. The solution 2 is supplied to a nozzle and
situated at a suitable position in the electrostatic field, and the
solution is drawn from the nozzle by the electric field to form a
filament. Any suitable apparatus may be used for this purpose, and
for example, an injection needle-type solution ejection nozzle 1
having a voltage applied by appropriate means such as a
high-voltage generator 6, may be set at the tip end of the
cylindrical solution holding tank 3 of an injector, and the
solution directed to the tip. The tip of the ejection nozzle 1 may
be placed at an appropriate distance from a grounded fiber
substance collecting electrode 5, so that a fiber substance is
formed between the tip and the fiber substance collecting electrode
5 when the solution 2 leaves the tip of the ejection nozzle 1.
[0069] It will be readily apparent to a person skilled in the art
that fine droplets of the solution may also be introduced into the
electrostatic field by a self-evident method. An example thereof
will now be explained with reference to FIG. 2. The sole condition
for this method is that the droplets must be held at a distance
from the fiber substance collecting electrode 11 which allows fiber
formation to occur in the electrostatic field. For example, an
electrode 10 directly opposing the fiber substance collecting
electrode 11 may be inserted directly into the solution 8 in the
solution holding tank 9 comprising a nozzle 7.
[0070] A plurality of nozzles may be used to increase the fiber
substance production speed when the solution is supplied from the
nozzle into the electrostatic field. The distance between the
electrodes will depend on the charge, the nozzle dimensions, the
spinning solution flow rate and the spinning solution
concentration, but a distance of 5-20 cm is appropriate for about
10 kV. The electrostatic potential applied will generally be 3-100
kV, preferably 5-50 kV and more preferably 5-30 kV. The desired
potential may be created by any suitable method.
[0071] The explanation given above is for an electrode also serving
as the collector, but a member serving as the collector may be
situated between the electrodes as a collector separate from the
electrodes. Also, the shape of the collector may be selected so as
to yield a sheet or tube. In addition, for example, a belt-shaped
material may be set between the electrodes as a collector to allow
continuous production.
[0072] According to the invention, the solvent evaporates in
response to the conditions while the solution is being drawn to the
collector, thus forming a fiber substance. At ordinary room
temperature, the solvent will completely evaporate during the
period until the substance is collected on the collector, but the
drawing may be carried out under reduced pressure conditions if
evaporation of the solvent is inadequate. Also the temperature for
drawing will depend on the evaporation behavior of the solvent and
the viscosity of the spinning solution, but will ordinarily be
0-50.degree. C. Accumulation of the fiber substance on the
collector produces a fiber structure.
[0073] The method used for production of a cylindrical body
composed of the fiber structure of the invention is not
particularly restricted, but using a mandrel which has not been
mirror surface-finished as the collector for electrostatic spinning
is preferred since it will allow more convenient production of the
cylindrical body. Specifically, by forming the fiber structure to a
prescribed basis weight on the mandrel by electrostatic spinning
and then removing the fiber structure from the mandrel while
maintaining a suitable degree of friction, it is possible to
conveniently obtain a cylindrical body having a bellows-shaped
section.
[0074] The surface roughness of the mandrel is preferably 0.2-S or
greater, and more preferably 1.5-400-S.
[0075] When the fiber structure is removed from the mandrel having
a suitable surface roughness as described above, it is preferred to
apply stress only to one end of the fiber structure. The end of the
fiber structure may be secured and the mandrel pulled out in the
direction toward the secured end to apply stress only to that
end.
[0076] Also, when the fiber structure is formed on the mandrel by
electrostatic spinning, it is preferred to rotate the mandrel in
the circumferential direction to form a more uniform cylindrical
body.
[0077] The cylindrical body obtained according to the invention may
be used alone, but it may also be used in combination with other
members for reasons of handleability or other required performance.
For example, by combining the cylindrical body with an elastic body
made of collagen or the like, it is possible to construct a member
exhibiting optimal elasticity and strength.
[0078] The source of the collagen used for the invention is not
particularly restricted, and it may be derived from any organism
such as a mammal, bird, fish or the like. Collagen produced by
cells such as bacteria, mold or yeast may also be used.
Organism-derived collagen is preferably mammalian collagen, while
collagen from cells such as bacteria, mold or yeast may be a
recombinant form obtained by gene manipulation. There is also no
particular restriction on the chemical structure of the collagen,
which may be acid-solubilized collagen, neutral salt-solubilized
collagen, enzyme-solubilized collagen, alkali-solubilized collagen
or the like. Any desired amino acid sequences, such as
telopeptides, of the collagen, as well as saccharides bonded to the
collagen, may be removed depending on the purpose of use, and
atelocollagen is preferred.
[0079] When the collagen is isolated from an organism, there are no
particular restrictions on the method of isolation. The soluble
components extracted with aqueous acidic solutions or aqueous
alkaline solutions are preferred for use. The collagen obtained by
extraction may be used directly in the form of an aqueous acidic
solution or aqueous alkaline solution, but it is preferred to
remove the excess low molecular ions by dialysis or ion
exchange.
[0080] The means for forming the composite of the fiber structure
and collagen according to the invention is preferably the following
method. Preferably, a solution of the collagen dissolved and/or
dispersed in an appropriate solvent is impregnated into the fiber
structure and then fixed by at least one method such as gelling,
crosslinking or drying, to form a collagen network.
[0081] In this case, if the collagen dissolves in the solvent it
may be utilized as a collagen solution, and if it does not dissolve
in the solvent it may be utilized as a dispersion. Also, when a
portion of the collagen dissolves or swells but does not completely
dissolve, both the solution and dispersion may be utilized for the
invention.
[0082] Any solvent may be selected, including water, amide-based
solvents such as dimethylacetamide and sulfone-based solvents such
as dimethylsulfoxide, but water is preferably used. In addition, an
inorganic salt such as calcium chloride or lithium chloride, a
polyhydric alcohol such as glycerin or polyethylene glycol or a
surfactant such as glycerin monostearate may be mixed into the
solvent if necessary.
[0083] There are no particular restrictions on the method of
impregnating the collagen into the fiber structure, and it may be
carried out at ordinary pressure, under reduced pressure or under
pressurization. A die may also be used to form an appropriate shape
for the cylindrical body.
[0084] Gelling is a procedure whereby the collagen is gelled by
heating under neutral conditions, and there are no particular
restrictions on the reagent used for pH adjustment. Crosslinking
involves reacting the collagen with a compound having two or more
functional groups which can react with collagen, and it is
preferred to use a compound with a carbodiimide group or a compound
with an active ester group.
[0085] The collagen concentration of the collagen solution,
dispersion or semi-solution is preferably at least 0.1% and no
greater than 10%. It is more preferably in the range of at least
0.2% and no greater than 8%.
[0086] The cylindrical body disclosed by the present invention may
be lyophilized if necessary. The conditions for lyophilization are
not particularly restricted, but preferably the lyophilization
temperature is no higher than -5.degree. C., and the vacuum degree
during lyophilization is no greater than 100 MPa.
[0087] The collagen impregnated into the fiber structure may be a
porous form depending on the purpose. The method of forming pores
is not particularly restricted, and sponge-like pores produced by
lyophilization are also desirable for use. The collagen may also
contain particles which are soluble in organic solvents, and a
method may be employed for their subsequent extraction with an
organic solvent. The fiber surfaces may also be coated with
collagen for maximum utilization of the spaces of the fiber
structure.
[0088] The composite obtained according to the invention may be
used alone, but it may also be used in combination with other
members for reasons of handleability or other required performance.
For example, additives such as glycerin or polyethylene glycol may
be included in order to increase the flexibility of the composite
as a whole, or proteins such as growth factors and cytokines may
also be added.
EXAMPLES
[0089] The present invention will now be explained in greater
detail through the following examples, with the understanding that
the invention is in no way limited to these examples.
[0090] The polylactic acid (Lacty9031) used in these examples is a
product of Shimadzu Laboratories, and the methylene chloride (high
grade) used is a product of Wako Pure Chemical Industries Co.,
Ltd.
Example 1
[0091] A dope was prepared by mixing 1 g of polylactic acid and 8 g
of methylene chloride at room temperature (25.degree. C.). An
apparatus such as shown in FIG. 2 was used for 5 minutes of
discharge of the solution to a fiber substance collecting electrode
5 (2 mm diameter, 200 mm length, 70-S surface roughness), causing
rotation at 60 rpm. During this time, the collecting electrode 5
was rotated 150 rpm in the circumferential direction. The inner
diameter of the ejection nozzle 1 was 0.8 mm, the voltage was 12
kV, and the distance from the ejection nozzle 1 to the fiber
substance collecting electrode 5 was 10 cm. The end of the fiber
structure collected at the fiber substance collecting electrode 5
was held fixed against a finger while the fiber substance
collecting electrode 5 was pulled out toward the end fixed against
the finger, to obtain a polylactic acid tube. The obtained
polylactic acid tube had a diameter of 2 mm, a length of 20 mm, a
basis weight of 20 g/m.sup.2, a bellows-shaped section spacing of
0.5 mm and a bellows-shaped section depth of 0.1 mm. The Young's
modulus and yield elongation of the obtained molded article were
measured using a Tensilon device (INSTRON) with reference to
DIN53507, 53504. The results are shown in Table 1. TABLE-US-00001
TABLE 1 Physical property values for materials Spacing of Basis
bellows- Young's Yield weight shaped modulus elongation Material
(g/m.sup.2) section (mm) (MPa) (%) Example 1 Polylactic 20 0.5 20
50 acid Example 2 Polylactic 40 0.5 35 30 acid Comp. Ex. 1
Polylactic 100 0.5 170 5 acid Comp. Ex. 2 Polylactic 20 3.0 100 10
acid
Example 2
[0092] The same treatment was carried out as in Example 1, except
that the basis weight was 40 g/m.sup.2.
Example 3
[0093] A 2 mm-diameter rod was reinserted into the polylactic acid
tube obtained in Example 1, and this was fixed at the center of a 3
mm diameter tube. A 1.5 unit volume of a buffer solution containing
260 mM sodium bicarbonate, 200 mM HEPES and 50 mM sodium hydroxide
was mixed with a 10 unit volume of 0.3% aqueous (type II) collagen
solution by Koken Co., Ltd., while cooling on ice, and the mixture
was placed in the holding tube in which the polylactic acid tube
was fixed. A procedure in which the external atmosphere pressure
was reduced and restored to ordinary pressure was repeated three
times, and then the tube was kept at 37.degree. C. for gelling.
After gelling, the 2 mm diameter rod was pulled out and
lyophilization was carried out to obtain a collagen cylindrical
body.
[0094] The yield elongation of the obtained molded article was
measured using a Tensilon device (INSTRON) with reference to
DIN53507, 53504, giving a yield elongation value of 38%.
Comparative Example 1
[0095] The same treatment was carried out as in Example 1, except
that the basis weight was 100 g/m.sup.2.
Comparative Example 2
[0096] The same procedure was carried out as in Example 1, except
that a different fiber substance collecting electrode 5 (2 mm
diameter, 200 mm length, mirror surface finish (surface roughness:
=0.1-S)) was used. The same treatment was carried out as in Example
1, except that the obtained polylactic acid tube had a basis weight
of 20 g/m.sup.2 and a bellows-shaped section spacing of 3.0 mm.
Comparative Example 3
[0097] A dope was prepared by mixing 0.5 g of polylactic acid and
10 g of methylene chloride at room temperature. The dope was packed
into an HG-S Spray Gun (product of Tamiya Inc.) having a
nozzle-aperture of 0.2 mm, and an air pressure of 0.08 MPa was used
for blowing into a rotating 2 mmf diameter rod. The fiber structure
formed on the rod surface was removed off, producing a fiber
structure with no bellows-shaped section, and having a basis weight
of 50 g/m.sup.2 and a thickness of 0.3 mm. This was used to form a
composite with collagen in the same manner as Example 3, and the
yield elongation was measured to be 8%.
INDUSTRIAL APPLICABILITY
[0098] According to the invention it is possible to obtain a
collagen/fiber composite structure exhibiting excellent
stretchability. The collagen composite may be utilized as a
vessel-substituting material such as an artificial vessel, or for
regeneration of nerves or urinary ducts. It may also be employed as
a cell culturing support in a test tube, or as an experimental
material for cell evaluation.
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